Dowel device for a concrete machine and concrete machine equipped with such a dowel device

ABSTRACT

Improved dowel device for a concrete machine which mainly consists of a series of insertion elements ( 19 ) for dowels ( 3 ) which is provided with an output pipe ( 27 ) for dowels ( 3 ) at the bottom, and a push-out mechanism ( 30 ) for dowels ( 3 ) whereby the push-out mechanism ( 30 ) of each insertion element ( 19 ) is formed of a chain ( 31 ) which is guided over two chain wheels ( 32 - 33 ) placed on top of one another and a flexible blade ( 34 ) which is fixed to the chain ( 31 ) with one far end and which is provided with a pressure piece ( 37 ) on the other far end, whereby the blade ( 34 ) is guided over a guide at the bottom of the second compartment which bends off the blade ( 34 ) in the direction of the output pipe ( 27 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention concerns an improved dowel device for a concrete machine, in particular a concrete machine for leveling concrete, of the type whereby poured concrete is distributed over a pre-determined width and this concrete is skimmed off at a certain thickness.

Such concrete machines are used, as is known, for spreading out and smoothing concrete in order to form a floor, slab, road or the like, whereby specific molded patterns can be provided in the formed road—either or not simultaneously—such as a gutter, a standing edge, a concrete guard rail or the like.

2. Discussion of the Related Art

It is known that such concrete machines are usually built of a mobile chassis, under which a number of tools are fixed, which are designed among others to distribute the concrete poured in front of the machine, to more or less even it, vibrate it and finally smooth it out, such that, after the concrete machine has passed, an entirely finished road is obtained, whereby one only has to wait for the concrete to harden and possibly provided expansion joints must be filled.

It is known to equip such concrete machines with a dowel device as well for providing dowels in the concrete, usually at the expansion joints. Such dowels are reinforcement rods, usually having a length of about half a meter, which are provided in the longitudinal direction of the road. Usually, a whole series of such dowels are provided next to one another, at mutual distances of 20 to 30 cm.

The dowel devices used hereby are devices which make it possible to provide dowels at a certain depth in the concrete near vibrating needles with which the concrete machine is equipped, as a result of which the dowels are embedded well in the concrete.

Such concrete machines and dowel devices are known from EP 1.284.323, whereby dowels are loaded in upward directed insertion elements, which insertion elements are situated at mutual distances from each other and are distributed over de width of the concrete machine, and whereby the dowels are pushed out of the above-mentioned magazines into the concrete via an output pipe at the bottom of every insertion element by means of a push-out mechanism.

Although these known dowel devices give good results in practice, they are disadvantageous in that they are relatively complex and sensitive to blocking, due to the fact that, on the one hand when loading the insertion elements, the falling motion of the dowels cannot be controlled and, consequently, the dowels can block in the insertion elements in a slanting position, and on the other hand, the push-out mechanism of every insertion element does not always exert an axial and centered push-out force on the dowels, due to the long lever arm of the push-out mechanism on the other hand, as a result of which obstructions may occur in this case as well.

Another disadvantage is that with the known dowel devices, the insertion elements are open at the top, as a result of which dirt and other unwanted elements may fall in the insertion elements, which may lead to obstructions or blockings.

The present invention aims to remedy one or several of the above-mentioned and other disadvantages.

SUMMARY OF THE INVENTION

To this end, the invention concerns an improved dowel device for a concrete machine which consists of a mobile chassis to which the dowel device is or can be fixed, which mainly consists of a series of insertion elements for dowels which are erected widthwise at a distance from one another in the concrete machine, and which consist of a housing directed upward and in the driving direction of the concrete machine with a first compartment in which dowels can be stacked and which is provided with an output pipe for dowels, and a second compartment in which a push-out mechanism for dowels is provided at the bottom, and whereby both compartments are connected at the bottom via a passage, characterized in that the push-out mechanism of each insertion element is formed of a chain which is guided over two chain wheels placed on top of one another and a flexible blade which is fixed to the chain with one far end and which is provided with a pressure piece on the other far end, whereby the blade is guided over a guide at the bottom of the second compartment which bends off the blade through the above-mentioned passage in the direction of the output pipe.

An advantage of such a dowel device according to the invention is that it has a relatively simple construction and occupies relatively little space in the driving direction of the concrete machine, as a result of which more space remains for other tools.

Another advantage is that, thanks to the construction of the push-out mechanism, the forces exerted by the push-out mechanism on the lower dowel in the first compartment are always axially directed according to the longitudinal axis of the dowel and in line of the output pipe, as a result of which can be avoided that a dowel might get stuck in the insertion element while being pushed out.

The improved dowel device according to the invention is preferably provided with an automatic loading system to load the dowels in the insertion elements, whereby this loading system contains a mobile trolley provided widthwise in relation to the concrete machine above the insertion elements.

An advantage of such an automatic loading system is that the insertion elements can be loaded quickly and automatically.

According to a preferred embodiment, a valve is provided in each insertion element, at the top, which can receive a dowel falling from the trolley in the insertion element concerned and which can subsequently drop this dowel in a controlled manner in the insertion element concerned.

This valve offers the advantage that the fall of the dowel is interrupted and that the dowel is first received on this valve so as to stabilize it first and to subsequently, when it lies still on the valve, be lowered in a soft and controlled manner in the insertion element, as a result of which the dowel is prevented from getting stuck in the insertion element during its free fall.

The valve is preferably a stop valve which can stop up the insertion element so as to prevent dirt from falling in the insertion element.

Said valve is also preferably provided with a control element which can work in conjunction with the above-mentioned trolley, such that when the trolley passes over an insertion element, a dowel falls in the insertion element.

The invention also concerns a concrete machine which is equipped with an improved dowel device as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better explain the characteristics of the invention, the following preferred embodiment of an improved dowel device according to the invention and of a concrete machine which is provided with such a dowel device is given as an example only without being limitative in any way, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic side elevation which represents a partial section of a concrete machine provided with an improved dowel device according to the invention;

FIG. 2 represents the section of the dowel device indicated by the frame F2 in FIG. 1 to a larger scale;

FIG. 3 represents a section as that in FIG. 2, but for another position;

FIGS. 4, 5 and 6 represent sections according to the respective lines IV-IV, V-V and VI-VI of FIG. 2.

DESCRIPTION OF THE PREFERED EMBODIMENT

As is represented in FIG. 1, the invention concerns a machine, in particular a concrete machine 1 for forming a concrete road 2 provided with dowels 3.

The concrete machine 1 mainly consists of a frame 4 which either or not is telescopic in the width and/or in the length and which is mobile thanks to for example supporting elements 5 situated on the angular points, which are provided for example with caterpillar tracks 6, which can be driven by means of engines that are not represented in the figures.

To the frame 4 and/or to the supporting elements 5 are in this case fixed several tools for realizing the concrete road 2.

Depending on the application, several tools are either or not used.

In the example of FIG. 1, these tools respectively consist of schematically indicated means 7 for spreading concrete 8 poured in front of the concrete machine 1, an improved dowel device 9 according to the invention for the insertion of the dowels 3, means 10 for vibrating the concrete, one or several moulds 11 and a finishing element 12.

The means 7 can be of different nature and they may consist for example of a plow for spreading the concrete 8 and/or of a driven element, such as an Archimedean screw, for distributing the concrete 8.

The means 10 for vibrating the concrete preferably consist, as is represented in FIGS. 1 and 2, of a series of known vibrating needles 13 which reach into the concrete 8 while processing the concrete 8, preferably up to underneath the mould 11.

The mould 11 actually consists of a large jig with which the concrete is pressed into a certain shape and is simultaneously provided with a smooth surface. When manufacturing a conventional concrete road, the mould is made straight, for example as a profile with a section as represented in FIG. 1, which extends over the working width of the concrete machine, in other words over the width of the concrete road to be built. It is clear that this can have special shapes as well and can be composed of several parts, for example so as to form a gutter, a standing edge or the like at a concrete road.

Moreover, several of such moulds 11 can be used which can be moved along each other, such that the working width can be adjusted. When discussing a mould 11 hereafter, it is clear that this also applies to embodiments whereby several of such moulds are present.

The finishing element 12 in FIG. 1 consists of a smoothing board which can be systematically moved over the formed surface 14 of the concrete road 2.

Naturally, the means 7 and the finishing element 12 are optional.

In the given example, the dowel device 9 is situated, according to the driving direction V of the concrete machine 1, in front of and/or near the mould 11 while concreting.

As is clearly visible in FIG. 2, the dowel device 9 contains a tray 15 or U-shaped guide with a bottom 16 and standing side edges 17, whereby this tray 15 is fixed to the frame 4 or is suspended to it and extends widthwise in relation to the concrete machine, and whereby grooves 18 are provided in the bottom 16 which extend widthwise in relation to the concrete machine 1, in other words crosswise in relation to the concrete road 2 to be realized, at regular distances from each other, and which are evenly distributed over the width of the above-mentioned tray 15.

The dowel device 9 contains a series of insertion elements 19 for dowels 3 which make it possible to insert dowels 3, when forming the concrete road 2, in the liquid concrete 8, whereby each of these insertion elements 19 is provided under an above-mentioned groove 18.

The insertion elements 19 and the vibrating needles 13 are alternately erected next to each other, as is clearly represented in FIG. 4.

As is represented in the FIGS. 2, 5 and 6, the insertion elements 19 consist of upward directed elements, each with a housing 20 of a limited width which extends mainly in a vertical plane, parallel to the driving direction V of the concrete machine 1, whereby every insertion element 19 is fixed to the above-mentioned bottom 16 of the tray 15, at the top, via a conical part 21.

The insertion elements 19 are fixed to the tray 15 in such a manner that, while the concrete machine 1 is in use, at least during the periods in which dowels 3 must be provided in the concrete 8, they extend into the concrete 8 more particularly they are situated with their bottoms 22 of the housing 20 in the concrete 8.

Said insertion elements 19 each contain two compartments, a first compartment 23 on the one hand which serves as a magazine and in which dowels 3 can be horizontally stacked, and a second compartment 24 on the other hand which is connected to the first compartment 23 via a passage 25 at the bottom.

The first compartment 23 is provided at the bottom on the back wall 26 of the housing 20 of each insertion element 19 with an output pipe 27 which mainly extends in the driving direction V of the concrete machine 1 and which forms a passage through which the dowels 3 can be axially pushed from the first compartment 23 into the concrete 8.

On the free end of the output pipe 27 is provided a bush 28 which is provided at its inner wall with a silicone coating 29 which can form a sealing around a dowel 3 which is pushed outward, in order to prevent concrete 8 from penetrating into the insertion element 19 via this output pipe 27.

In the second compartment 24 of each of the insertion elements 19 is provided a push-out mechanism 30 which makes it possible to push the dowels 3 out of the first compartment 23 via the output pipe 27 into the liquid concrete 8.

The push-out mechanism 30 in this case consists of a chain 31 which is guided over two chain wheels 32 and 33 placed on top of each other, in this case vertically on top of each other, which are each bearing-mounted in the housing 20 in a rotating manner, and whereby a flexible blade 34 is fixed to the outside of the chain 31, for example made of spring steel, in this case by means of screws or bolts 35 which are screwed through the far end of the blade 34 and through the chain 31 in a stop block 36.

The above-mentioned blade 34 made of spring steel extends vertically against the chain 31 and is guided with its free end, which is provided with a pressure piece 37 over a bent guide 38 at the bottom of the second compartment 24, such that this free end extends horizontally opposite the passage 25 between the first and the second compartment, 23 and 24 respectively, as is represented in FIG. 2 and bends off the blade 34 through the passage 25 in the direction of the output pipe 27, in particular in the direction of the extension of the output pipe 27, preferably in a direction in the extension of the bottom 22 of the insertion element 19.

On the inside of the chain 31 is provided a stop slat 39 with two stop-forming far ends 40 and 41, such that the chain 31 with its stop block 36 can move to and fro between these two stop-forming far ends 40 and 41, in particular between a first farthest position, as represented in FIG. 2, whereby the stop block 36 is situated against the top stop-forming far end 40, and the blade 34 is entirely withdrawn in the second compartment 24, and a second farthest position where the stop block 36 touches the bottommost stop-forming far end 41 and the blade 34 extends horizontally with its free end over a certain length in the first compartment 23 as represented in FIG. 3, preferably with the pressure piece against or practically against the output pipe 27.

The push-out mechanism 30 comprises, as represented in FIG. 6, a drive 42 which in this case is common to all insertion elements 19 and which is formed of a common shaft 43 which is in this case formed of a series of pieces connected to each other and which extends in the width of the tray 15 through the second compartments 24 of the insertion elements 19 and onto which the topmost chain wheel 32 of each of these insertion elements 19 is fixed.

The above-mentioned shaft 43 is driven via a central motor 44 and one or several drive belts or chains 45, whereby this motor 44 is electrically connected to a control box 46 which can drive the motor 44 in both directions of rotation.

In the front wall 47, in the extension of the above-mentioned output pipe 27, is provided a control opening 48 which can be sealed by means of a stop 49.

The dowel device 9 is further provided with an automatic loading system 50 in the form of a trolley 51 with wheels 52 provided in a mobile manner in the above-mentioned tray or gutter-shaped guide 15 and which can be moved to and fro between the standing side edges 17 of this tray or guide 15, widthwise in relation to the concrete machine 1, whereby this trolley 51 is provided with a drive which is not represented in the figures and whereby the standing side edges 17 form a guide for the trolley 51.

The trolley 51 is made tub-shaped with standing walls 53 and a bottom 54 which slants down widthwise in relation to the concrete machine 1 which is fixed with one end to an above-mentioned standing wall 53 and which rests with its other end on a key-shaped element 55 whose width A is larger than the width B of the grooves 18 and which, together with the trolley 51, moves over or right above the bottom 16 of the tray 15.

The trolley 51 is provided, on the lower edge of the slanting bottom, with a groove-shaped outlet 56 whose width essentially corresponds to the thickness of the dowels 3 and through which the dowels 3 can fall out of the trolley 51 via the above-mentioned grooves 18 on the bottom 16 of the tray 15 in the insertion elements 19.

The groove 56 is in this case formed between the free edge of the bottom 54 and the opposite standing wall 53 onto which, above this groove 56, is provided a guiding strut 57 with a triangular cross section.

In each of the insertion elements 19 is provided a valve 58 to collect dowels 3 falling from the trolley 51 in the insertion element 19 concerned, to stabilize them and subsequently drop them in a controlled manner in the insertion element 19.

In the given example, the valve 58 is a stop valve in the form of an angle section with legs 59 and 60 which is hinge-mounted in its longitudinal direction around a shaft 61 and which can hinge between two extreme positions, namely a first position in which, as is represented in FIG. 5 for the left insertion element, the first compartment 23 is sealed by means of the leg 59 and the leg 60 is directed upward, and a second position in which, as is represented for the other two insertion elements of FIG. 5, the leg 59 is tilted downward so as to open the compartment 23, whereby the first compartment 23 is sealed in this position by means of the other leg 60.

Thus, in both positions, the compartment 23 is sealed, thus preventing dirt from falling in this compartment 23, which would entail the risk for the dowels 3 to become blocked in an unwanted position in the insertion element 19 due to the dirt.

The valve 58 is provided with a control element 62 in the form of a lip which can work in conjunction with the trolley 51 so as to move the valve between the above-mentioned extreme positions and which is positioned such that it rests on the bottom 16 of the tray 15 in the first position of the stop valve 58 and that it is directed upward in the second position of the stop valve 58 and extends above the bottom 16 of the tray 15 so as to be able to work in conjunction with the key-shaped element 55 of the trolley 51.

Further, the dowel device 9 of the concrete machine 1 can be equipped with a detection device which is not represented in the figures and which can work in conjunction with elements erected next to the concrete road 2 to be formed, for example pegs provided especially to that end, and which can activate the drive 42 of the push-out mechanism 30 and the drive of the trolley 51 in an appropriate sequence.

The working of the concrete machine 1 and in particular of the dowel device 9 can be easily derived from the figures and is mainly as described hereafter.

First, the trolley 51 is filled with a required number of dowels 3 which are stacked on the downward slanting bottom 54 of the trolley 51.

Next, the compartments 23 of the insertion elements 19 are filled by moving the trolley 51 to and fro over the width of the tray 15, whereby, when the trolley 51 moves to the right and the key-shaped element 55 moves over the insertion elements 19, the stop valves 58 are tilted in their first position and whereby, when the groove 56 of the trolley 51 is situated above the insertion element 19 concerned, a dowel 3 falls onto the leg 59 which in this position seals the compartment 23 of the insertion element 19.

When the trolley 51 moves further to the right, the control element 62 in the form of a lip will no longer be stopped by the key-shaped element 55, and the leg 59 of the stop valve 58 will be able to tip over due to the weight of the dowel 3, as a result of which the dowel 3 concerned falls in the first compartment 23 of the insertion element 19 in a controlled manner.

An advantage of this valve 58 is that, before the dowel 3 falls in the first compartment 23 of the insertion element 19, the dowel 3 is first stabilized on the valve 58, thus preventing the dowel 3 from moving slantingly in the insertion element 19 during its falling motion, thus blocking the lead-through of dowels 3.

Optionally, on the inside of the back wall 26, is provided a slanting guide 63 which makes sure that the dowel 3 ending up on the bottom 22 is situated at a distance from the above-mentioned back wall 26, so as to prevent that this dowel 3 might end up on a dowel 3 which had been previously provided in the output pipe 27.

While loading the insertion elements 19, the blades 34 of the push-out mechanism 30 are entirely withdrawn in the second compartment 24, thus preventing the dowels 3 from ending up on the pressure piece 37 while they are being loaded, as a result of which they would be directed slantingly, which would hinder the good working of the dowel device 9.

It is clear that, thanks to a to-and-fro movement of the trolley 51, the insertion elements 19 can systematically be filled with a required number of dowels 3.

The speed of the trolley 51 is selected such that each time an insertion element 19 is being passed, only one dowel 3 at a time ends up in the insertion element 19.

Once there are a sufficient number of dowels 3 in the insertion elements 19, the push-out mechanisms 30 of the insertion elements 19 are moved to and fro once by activating the motor 44 of the common drive 42.

To this end, the motor 44 is first activated in one sense of rotation, as a result of which the shaft 43 is turned and the chains 31 of the push-out mechanism 30 are driven, such that the blades 34 made of spring steel are pushed down by the chains 31 and the pressure piece 37 of each of said blades 34 is moved over the bottom of the insertion elements 19 by the bent guide 38, thereby pushing the lower dowel 3 out of the compartment 23 in the output pipe 27.

The form of the pressure piece 37 is preferably such that it can hold the front end of a dowel 3, in order to make sure that the lower dowel 3 which is moved by the push-out mechanism is pushed in the axial direction in the output pipe 27, thus preventing blockages.

After the dowel 3 has been pushed in the output pipe 27, the motor 44 is activated in the other sense of rotation, as a result of which the blades 34 and the pressure pieces 37 are withdrawn in the second compartment 24 in the reverse sense and as a result of which the stacked dowels 3 drop to the bottom 22 of the insertion element 19.

This creates a condition which is ready for use as is represented in FIG. 3, whereby two dowels 3 are situated in line, one after the other, one of which is situated in the output pipe 27, ready to be inserted in the concrete 8.

When forming the concrete road 2, concrete 8 is poured in front of the concrete machine 1. This concrete 8 is first spread out roughly by the above-mentioned means 7, after which, by means of the mould 11, the actual concrete road 2 is formed. By means of the finishing element 13 can be carried out an additional smoothing operation.

As soon as the concrete goes under the mould 11, it is vibrated by means of the vibrating needles 13, as a result of which the concrete is made compact and homogenized.

During the concreting, the insertion elements 19 slide through the concrete 8.

When a series of dowels 3 is to be inserted, this is done in the manner as is systematically represented in the FIGS. 2 and 3, whereby while moving the concrete machine 1 in the driving direction V, the push-out mechanisms 30 of the insertion elements 19 are simultaneously activated as described above.

As a result, the lower dowel 3 is pushed in the first compartment 23 of each insertion element 19 in the output pipe 27, such that the dowel 3 which is situated in the output pipe 27 at that time is in turn pushed out of the output pipe 27 into the liquid concrete 8.

The control box 46 is set such that the speed at which the drive 42 controls the push-out mechanisms 30 is synchronized with the driving speed of the concrete machine 1, as a result of which the dowels 3 stay in place in relation to the environment as if it were.

Thus, the released dowels 3 that are inserted in the concrete 8 are systematically enclosed by the concrete in their longitudinal direction, whereby, partly due to the effect of the vibrating needles 13, a sound compaction of the concrete 8 round the dowels 3 is obtained.

After a first series of dowels 3 has been inserted, the common drive 42 of the push-out mechanisms 30 is excited in the reverse sense, as a result of which the blades 34 of the push-out mechanisms are drawn back into the second compartment 24 and are prepared to push a following series of dowels 3 in the concrete in an analogous manner as described above, after the concrete machine 1 has moved somewhat.

It goes without saying that the concrete machine 1 and the dowel device 9 can be operated manually, but that the whole operation of building a concrete road 2 is preferably done entirely automatically, whereby the above-mentioned control box 46 will then control the concrete machine 1 and the dowel device 9 in an appropriate manner as a function of the signals of the above-mentioned detection device which can work in conjunction with pegs that are erected at regular distances from one another along the trajectory of the concrete road 2 to be built, so as to indicate in which places dowels 3 must be inserted in the concrete 3.

Although the dowels 3 are preferably inserted parallel to the driving direction V of the concrete machine 1, it is not excluded to realize this at a slight angle of for example 15.

It is clear that the loading system 50 can be omitted in a simpler embodiment of the dowel device 9 and that the insertion elements 19 can be manually preloaded with a required number of dowels 3.

It goes without saying that the valve 58 can be realized in other forms and that also the control thereof through the movement of the trolley 51 can be realized in other ways.

Moreover, said valve 58 must not necessarily entirely seal the first compartment 23 of an insertion element 13, but it may be sufficient for the insertion element 19 to be sealed only partly, but to a sufficient degree so as to be able to collect a dowel 3 from the trolley 51 and to be able to stabilize it before it enters the insertion element 19.

Naturally, instead of a trolley 51, use can also be made of a carriage for loading the dowels 3.

The present invention is by no means limited to the embodiment given as an example and represented in the accompanying drawings; on the contrary, such a dowel device according to the invention and a concrete machine provided with such a dowel device can be made in all sorts of shapes and dimensions while still remaining within the scope of the invention. 

1. A dowel device for a concrete machine including a mobile chassis to which the dowel device is or can be fixed, the dowel device having a width relative to a movement direction of a concrete machine to which it may be fixed, and comprising a series of insertion elements for dowels which are erected widthwise in relation to the dowel device at a distance from one another, and further comprising a housing directed upward, said housing having a first compartment in which dowels can be stacked and an output pipe for dowels at the bottom of said first compartment, and a second compartment in which a push-out mechanism for dowels is provided, and wherein both compartments are connected at their respective bottoms via a passage, said push-out mechanism of each insertion element comprising a chain which is guided over two chain wheels disposed one above the other and a flexible blade which is fixed to the chain and having one far end and which is provided with a pressure piece on another far end, and wherein the blade is guided over a guide at the bottom of the second compartment, said guide configured to bend off the blade through said passage in the direction of the output pipe.
 2. The dowel device for a concrete machine according to claim 1, wherein one of the chain wheels is provided with a drive to move the pressure piece of the push-out mechanism at least between a first extreme position in which the blade and the pressure piece are entirely withdrawn from the second compartment and a second extreme position in which the blade extends into the first compartment with a pressure piece up against or practically against the output pipe.
 3. The dowel device for a concrete machine according to claim 2, wherein the extreme positions of the push-out mechanism are determined by a stop block which is fixed to the chain and two stop-forming elements working in conjunction with it.
 4. The dowel device for a concrete machine according to claim 1 wherein the top chain wheels of the insertion elements are provided on a common shaft which is driven by a common drive.
 5. The dowel device for a concrete machine according to claim 2, wherein the drive is electrically connected to a control box arranged such that when the drive is activated for pushing out the dowels, the speed at which the dowels are pushed out of the insertion elements is equal or practically equal to the driving speed of a concrete machine to which the dowel device is fixed.
 6. The dowel device for a concrete machine according to claim 1, wherein the configuration of the pressure piece is such that it can hold a dowel at its far end.
 7. The dowel device for a concrete machine according to claim 1, wherein the blade is made of spring steel.
 8. The dowel device for a concrete machine according to claim 1, wherein the dowel device is provided with an automatic loading system for loading the dowels in the insertion elements.
 9. The dowel device for a concrete machine according to claim 8, wherein the loading system comprises a trolley with a bottom slanting down widthwise and a groove-shaped outlet for the dowels, which trolley can be moved to and fro, widthwise on the bottom of a tray or guiding gutter which is fixed or can be fixed to a concrete machine and onto which the insertion elements are fixed, each time under a groove in the bottom through which the insertion element can be loaded.
 10. The dowel device for a concrete machine according to claim 8, wherein in each insertion element is provided a valve at the top which is arranged to receive a dowel which falls from the trolley in the respective insertion element and which can subsequently drop this dowel in a controlled manner in the respective insertion element.
 11. The dowel device for a concrete machine according to claim 10, wherein the valve is a stop valve which seals the insertion element at the top.
 12. The dowel device for a concrete machine according to claim 10, wherein the valve is formed of an angle section with legs which is hinge-mounted around a shaft in its longitudinal direction and which is hinge-mounted between a position in which the first compartment is sealed by means of one leg and a second position in which this leg is tilted downward and the other leg seals the first compartment.
 13. The dowel device for a concrete machine according to claim 12, wherein the valve is provided with a control element which is arranged to work in conjunction with the trolley so as to move the valve between said extreme positions when the trolley is moved over the respective insertion element.
 14. The dowel device for a concrete machine according to claim 13, wherein the control element is formed of a lip which is fixed to the valve in such a manner that, in the first position of the valve, it rests on the bottom of the tray, and in the second position of the valve it is directed upward and extends above the bottom of the tray so as to be able to work in conjunction with the trolley.
 15. The dowel device for a concrete machine according to claim 14, wherein the trolley is equipped with an element which moves over or right above the bottom and which can work in conjunction with the control element.
 16. The dowel device for a concrete machine according to claim 15, wherein the element is a key-shaped element on which the inclined bottom of the trolley rests.
 17. A concrete machine, comprising a dowel device according to claim
 1. 